This research focuses on the central unsolved problem of psychiatric epidemiology, the problem of how to measure psychiatric disorders independently of treatment status in general populations. The on-going study, based on previous research in this program, has involved construction of a new interview instrument, test of it over time with a probability sample consisting of about 200 New york City adults, and examination of the extent to which it can be administered by lay interviewers who are not clinicians rather than by psychiatrists. In addition, interviews have been conducted with an equivalent sample consisting of 131 adults who have provided "life change" ratings for stressful life events asked about in the above interview, and also "social desirability ratings" for the items on symptomatology and role functioning. The specific aims of this renewal application are: 1. To test and calibrate the new instrument with interview data from psychiatric patients and convicts. 2. To investigate further the reasons for sharp differences found in the amount of symptomatology reported to psychiatrists by contrast with lay interviewers for purpose of training lay interviewers to collect the above data. 3. To develop brief screening instruments based on the lengthy new interview that has evolved from work to date.